Vaillant ecoTEC plus VUI Series, Installation And Maintenance Instructions Manual

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0020308121_04 Installation and maintenance instructions
75
Code/meaning Possible cause Measure
F.024
The temperature increases too
quickly.
Fault in the electrical connec-
tion for the return temperature
sensor
▶
Check and, if required, replace the wiring harness between the
PCB and sensor, including all plug connections.
Flow temperature sensor de-
fective
▶
Check and, if required, replace the flow temperature sensor.
Return temperature sensor de-
fective
▶
Check and, if required, replace the return temperature sensor.
Pump blocked
▶
Check that the pump is working correctly.
Pump runs with insufficient out-
put
▶
Check that the pump is working correctly.
3-port diverter valve defective or
blocked
▶
Check and, if required, replace the 3-port diverter valve.
Internal expansion vessel de-
fective
▶
Check the internal expansion vessel and replace it, if neces-
sary.
F.025
The flue gas temperature is too
high.
Wiring harness defective
▶
Check the wiring harness including all plug connections and, if
required, replace it (PCB plug X20, contact 14/15).
If present: Flue gas temperature
monitor has triggered
▶
Check and, if required, replace the flue gas temperature mon-
itor.
F.027
A flame signal has been detec-
ted while the burner is off.
Gas solenoid valve not leak-
tight
▶
Check that the gas valve assembly is working correctly and, if
required, replace it.
PCB defective
▶
Replace the PCB.
F.028
The flame signal was not detec-
ted during the ignition phase.
Hard ignition takes place 1. Check the heat exchanger, siphon, siphon adapter, siphon
hose (connection between the primary heat exchanger and
the siphon, and siphon hose outside of the product), flue
pipe adapter, unit housing, front casing and side section for
possible damage.
2. If required, replace any damaged parts immediately.
Gas isolator cock closed
▶
Open the gas isolator cock.
Gas connection pressure too
low
▶
Check the gas connection pressure.
Air in the gas supply (e.g. dur-
ing initial start-up)
▶
Reset the unit once.
Incorrect gas type set
▶
Check the gas type and the gas type setting under D.156 and
D.157 .
Gas valve assembly offset in-
correctly stored in
D.052 und
ggf. D.182
▶
Check the offset setting for the gas valve assembly.
Air intake pipe blocked
▶
Check and, if required, replace the air intake pipe.
Ignition failed 1. Check the ignition using check programme P.021 .
2. Product starts: Ignition electrode, ignition transformer, gas
valve assembly and fan are working, gas is flowing and the
gas volume is correct, no blockage or recirculation detected.
3. Product does not start and displays F.028 again: Carry out
the next check for the cause.
Gas flow pressure too low
▶
Check the gas flow pressure and the external gas pressure
switch.
Control electrode comes into
contact with the burner 1. Check the clearance between the control electrode and the
burner.
2. Check and, if required, replace the control electrode.
Ignition electrode defective
▶
Check and, if required, replace the ignition electrode.
Burner defective
▶
Check and, if required, replace the burner.
Condensate pump (if fitted)
defective
▶
Check and clean the condensate pump. Replace the condens-
ate pump, if required.
Gas valve assembly defect-
ive/incorrect spare part gas
valve assembly
▶
Check and, if required, replace the gas valve assembly.
Interruption in the wiring har-
ness
▶
Check the wiring harness including all plug connections and, if
required, replace it.
Earthing defective
▶
Check the product's earthing.
Ionisation flow interrupted
▶
Check the control electrode, the connection cable and the plug
connection.